The Top 5 Crashes on iOS

The first example’s remedy seems to be wrong.

I am not aware of any reason to test for "nil" in Objective-C, as that remedy suggests. Sending the "doSomething" message to "nil" should do nothing.

If SIGSEGV does occur for an object, it is probably for the exact opposite reason: you have a pointer that is NOT "nil" but it refers to something that has been freed. (Or, the SIGSEGV is not related to objects at all, and is caused by some other access such as plain C code.)